1. Field of the Invention
The present invention relates generally to a PM (permanent magnet) type step motor used to move a camera or an optical pickup lens of media related equipment and, more particularly, to a step motor having a stator unit including first and second stators which butt against and are coupled to each other and each have a bobbin and a yoke attached thereto, wherein a terminal block of the first stator is spaced apart from a terminal block of the second stator when the first and second stators butt against and are coupled to each other, thus allowing an automatic winding operation using winding equipment to be easily performed, and the step motor includes a bushing which has in a central portion thereof a through hole through which a rotating shaft passes and is of a two-stage structure having a small outer diameter part and a large outer diameter part on an outer circumference thereof, thus allowing the stator unit, the rotating shaft and a casing unit to easily be arranged along a single axis.
2. Description of the Related Art
Generally, a PM (permanent magnet) type step motor includes a rotor to which magnets are attached, and a stator which is spaced apart from the outer circumferences of the magnets by a predetermined interval, so that the step motor rotates in response to an external electric signal applied to the stator.
The step motor includes the rotor and the stator, with a casing provided around the outer circumference of the stator to protect and cover the stator.
The rotor includes a plurality of magnets which are provided on the outer circumference of a rotating shaft and are magnetized such that their N and S poles alternate, the rotor being inserted into the inside of the stator. The stator includes a bobbin which receives the coil and yokes which have a plurality of yoke teeth inserted into the inside of the bobbin.
The yokes are constructed such that the plurality of yoke teeth face and engage with each other.
The magnetic path of the magnets is formed to pass through the yoke teeth which engage with each other, so that the rotor of the step motor is rotated by external power applied to the stator.
The step motor includes one pair of bobbins which are coupled to face each other. A terminal block protrudes from the upper portion of each bobbin, and protects a connection terminal pin which applies external power to the coil received in the bobbin.
As the miniaturization of the step motor is required, its outer diameter is reduced. Here, the conventional step motor is problematic in that conducting an automatic winding operation using winding equipment is very difficult, because there is an interval between connection terminals and there is a spatial limit imposed when the connection terminal block is installed.